The present invention relates to a method for the assisted production of an oil effluent, more particularly a viscous effluent, contained in a geological formation lying over another formation which does not contain the effluent to be produced and which is impermeable to said effluent.
Description of the Prior Art
The method of the present invention allows better working of the formation containing the effluent to be produced, while limiting the number of wells to be drilled relatively to the methods used in the prior art, which may be illustrated by the U.S. Pat. No. 3 386 508.
In this prior patent, a main well is drilled as well as other wells which will be termed auxiliary wells. These auxiliary wells which are inclined join up with the main well at the level of the formation containing the effluent to be produced.
The production mechanism described in this prior patent resides in the fact that it is the portion of the auxiliary well situated in the formation to be produced which serves for collecting the effluent to be produced which is situated close to the auxiliary well.
Moreover, in this prior patent, production takes place by using the gravity phenomenon for draining the effluent towards the main well. Now, the intensity of the force of gravity is limited by the height between the roof of the formation containing the effluent to be produced and the position where the auxiliary well opens into the main well, when the formation containing the effluent to be produced is situated between two other formations which do not contain the effluent to be produced.
According to this prior patent, this height is at most equal to that of the formation containing the fluid to be produced.
The present invention provides a method for improving the recovery of the fluid to be produced.
This improvement results, for certain embodiments, in a better recovery rate due to the increase in the gravity effects allowing draining and in working an extended zone with a reduced number of wells.